The present invention relates to shock-absorbing systems for use in underground pulsed nuclear power plants in which the nuclear energy released by the explosions of nuclear devices is used for varied applications. These include the production of power, the generation of nuclear fissile materials or both. The general embodiment of such power plants is described and discussed in my U.S. Pat. No. 4,569,819 entitled PULSED NUCLEAR POWER PLANT (Ref. 1) and a paper submitted by Charles J. CALL and Ralph W. MOIR of the Lawrence Livermore National Laboratory to Nuclear Science and Engineering, dated May 27, 1988 (Ref. 2), entitled A Novel Fusion Power Concept Based on Molten Salt Technology: PACER Revisited.
One of the many technological problems related to such concepts is that of attenuation or dampening of the shock loading of whatever structures being used to contain the nuclear explosions. This problem is compounded by the fact that such containement must be provided many times over a lifetime period of the plant of thirty years or so. This, of course, is to happen without catastrophic failure. Ref. 1 and another paper published in Fusion Technology by Ralph W. MOIR (Ref. 3) entitled PACER Revisited of Nov. 18, 1988, address this very problem. Initially, Project PACER concept, as does Ref. 1, dealt with power plants in which the working fluid is water initially that is transformed into superheated steam by the energy release. This means that both peak operating pressures and temperatures are elevated to the point where survivability of structural elements operating in such environment is indeed questionable. In Ref. 3, the author attempts to shape the cavity wall and improve its anchoring to a surrounding rock structure in the hope that the rock structure will survive up to 200,000 explosions over a period of 30 years.
The inventor contention is that a more logical and promising approach is to isolate the surrounding rock structure from shocks that inevitably reach any wall that is directly exposed to the medium in which the detonation occurs. The inventor believes that the dampening of shock waves or containment of the fireball by thermo-hydrodynamic means is illusory. A decoupling of the effects of any interaction of the hot medium on such containment walls from the supporting and surrounding structure seems necessary. This is the role that the present invention embodiment assumes as applied to the pulsed nuclear power plant advanced in Ref. 1 and 2.
Such decoupling can be achieved by letting the impulse imparted by the shock wave interaction with a mobile rigid structure during a very short time be transferred to a static rigid structure holding the cavity over a much longer period of time. In the process of momentum transfer and kinetic energy conservation, the average loads exerted on the static structure are much lower than those which it would have to withstand were it not for the presence of the buffering action of a shock-absorbing system. Such buffering action of a shock-absorbing system can be accomplished by flexible and compressible structural elements located between the mobile and the static rigid structures.
In Ref. 1, the shock-absorbing system is located in and exposed to the medium before, during and after the detonation of the nuclear device. This renders access to the shock absorber system very unwieldy during the lifetime of the plant. In the concept advanced in Ref. 2, by comparison, the medium environment is even more hostile and practically impossible to deal with. However, in terms of medium peak pressures and temperatures, the static structure is exposed to much lower loads. This allows and justifies a repositioning of the shock-absorbing system, from inside the cavity to outside deformable and thus compliable walls of the cavity.